The effects of post-encoding physiological arousal and sleep quality on memory Restricted; Files Only

Cho, Linda (Spring 2024)

Permanent URL: https://etd.library.emory.edu/concern/etds/m900nv88t?locale=en%255D
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Abstract

Memory is typically enhanced for emotional events relative to neutral events, also known as the emotional enhancement of memory effect (Hamann, 2001). This enhancement of memory effect has been extensively studied with various visual and verbal stimuli that are inherently arousing, but very few studies have investigated this in a post-encoding arousal context (presenting arousing stimuli after encoding) (Nielson and Powless, 2007). The few that have studied effects of post-encoding arousal on memory performance have found conflicting results. Thus, this study aimed to examine recognition memory using the post-encoding arousal method, predicting that there would still be enhancement effects for neutral words with the presentation of negative stimuli afterwards. Given that there is substantial evidence for the effects of sleep quality on memory performance (Payne and Kensinger, 2018), we further predicted that memory enhancement effects would be stronger in those with higher sleep quality relative to lower sleep quality. Because post-encoding arousal enhances emotional memory (McGaugh et al., 2002), we predicted that greater increases in physiological arousal would be associated with larger memory enhancement effects. To investigate these hypotheses, we conducted an in-person between-subject experiment. Participants encoded 120 neutral words and 90 neutral word pairs, followed by a 10-minute delay, then an emotional arousal manipulation, in which either highly arousing negative films or neutral videos were presented. Recognition memory was assessed 24 hours later with a remember-recognition memory task. Contrary to predictions, the negative videos presented after encoding did not enhance subsequent recognition memory for the neutral stimuli. Similarly, better sleep quality and increased physiological arousal were not significantly correlated with recognition memory performance. Although results of the current study were inconsistent with predictions, it is possible that the delay between the encoding phase and the negative film presentation were too long, allowing us to speculate that post-encoding arousal effects, better sleep quality, and greater differences in arousal would enhance memory. Thus, future studies may benefit from shortening delay time between encoding and negative film presentation. 

Keywords: memory, post-encoding arousal, sleep quality, physiological arousal, emotions

Table of Contents

Abstract 1

Introduction 3

Materials and Methods 10 

Participants 10

Neutral Word Stimuli 11

Video Stimuli 11

Psychophysiology 12

Procedure 13

Statistical Analysis 18

Results 19

Discussion 27

References 33

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